Telephone-exchange system.



E. R. conwm. TELEPHONE EXCHANGE SYSTEM.

APPLICATION HLED JULY 15. I912.

1,11.,1.. Patented Nov. 23, 1915.

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E. R. CORWIN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JULY 15. I912.

Patented NW. 23, 1915.

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ELMER R. CORWIN, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO FRANK B. COOK COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Nov. 23, 1915.

Application filed July 15, 1912. Serial No. 709,407.

To all whom it may concern Be it known that I, ELMER R. CoRwIN,

invention there are operator controlled elec- I tro-magnetic switches, less in number than the telephone lines, for connecting the answering ends of link connectors with calling lines.

In accordance with another feature ofrmy invention there are employed electro-magnetic switches for connecting calling lines with calling line extensions extending toward called stations and which are herein shown as being themselves called lines, though the invention is not to be limited to the direct and immediate connection of called lines with the link connectors.

In accordance with another feature of the invention the operator controlled means which are employed for operating either or both kinds of switches are selected by calling line operated selector switches which also desirably associate calling line operated responsive devices, such as operators telephones, with calling lines.

I will explain my invention more fully by reference to the accompanying-drawings showing the preferred embodiment thereof and in wh1ch- Figures 1 and 2, taken collectively and read with the conductors at the left and right of the figures and at the upper portion thereof in alinement, illustrate an exchange system as constructed in accordance with the preferred embodiment of the invention to which embodiment the invention is not to be limited; and Fig. 3 is a detail view of some of the mechanism.

I have shown two telephone lines, the telephone stations illustrated happening to include telephone switch hooks 1, telephone ree -ators .pos tlons A, 13 having operators ceivers 2, transmitters 3, signal vreceivers 4t,

wipers 13 and condensers 5, two stations 120 and 190 belng illustrated with this apparatus. The telephone lines, in the embodiment of the invention illustrated, each terminates at the same exchange (though it will become apparent that the lines do not need to terminate at the same exchange in order to practice my invention) in multipled contacts 11 and multipled contacts 12 constituting waiting contacts of a plurality of switches, each link connector including nonmultipled contacts 13 that are individual thereto and WlllCll ZLI'B in the form. of switch wipers constituting parts of operator controlled switches for bringing the link connector terminals 13 into connection with calling line 1 terminals 11, 12. The link connector terminals 13 at the left or calling line end of a link connector, are thus adapted for engagement with contacts 11, 12 of a calling line, and have companion link connector terminals 13 at the other end of the same link connector, these latter terminals 13 being also controlled by the operator for the purpose of bringing them into connection with waiting contacts 11 12 belonging to a called telephone line. Thus each telephone line has its terminals 11, 12 which are employed when it is a calling line for extending it and which are not employed when it is a called line. Each telephone line also has its contacts 11 12 that are employed when it is a called line and are not employed when it is a calling line. The contacts 11 12 are multipled throughout the connecting or calling ends of the link connectors, being included in banks that are passed over by the eachlink connector (13 is accessible to callingline terminals 11, 12 and the called line end of each link connector (13 is accessible to called line terminals 11 12 The mechanism by which the terminals 11, 12, 11 and 12 are engaged by their wipers will be later hereinafter set forth,

and while I have shown the terminals 11 and 12 in Fig. 2 aspertaining to a telephone line, yet the invention is not to be limited to the nature of the line portions that are to be connected with calling lines by way of the contacts 11 12 In the drawings I have shown two op- Thus the calling line end of telephones 13, 1 1 that constitute one form of responsive device which may be selected by calling stations, these responsive devices being operable by calling parties after their selection though I do not limit myselfto a that aret'ree for selection.

As soon as a calling subscriber has re- 7 moved his telephone from its switch hook the selecting mechanism individual to the calling 'subscribers line is set into operation. The circuit that causes the operation of the selecting mechanism when a calling subscriber initiates a connection is traceable from the grounded battery 35 through the interrupter 34, the lower winding of the motor magnet 30, this lower winding constituting the motor winding, the bottom armature switch of relay 37 and its normal i contact, the upper armature switch of relay 39 and its normal contact, both sides of the calling line, and the telephone transmitter and receiver connecting both sides of the calling line, to the grounded relay 40. The interrupter 34 causes the intermittent energization of the motor winding of the magnet 80 whereby the armature of this motor magnet causes the pawl 32 to operate ,upon the ratchet wheel. 21 whereby the wipers carried by this ratchet wheel are brought into engagement with the set of waiting contacts pertaining to an idle operator. The wipers of the selecting devices are desirablynormallyout of contact with the waiting contacts and pass over these contacts in the process of selecting a responsive device at an operators position and which responsive device may be an ope-rators telephone. The responsive devices are free for selection when the circuits governing the responsive devices are in their normal or idle conditions. Each responsive device has a governing circuit that may be traced from the ground 44, the switch of grounded common battery 35.

.magnet 43,. the selected waiting contact 27, the wiper 24: engaging the same, the normal follow-up contact of the armature switch 4701 relay 37, the winding of relay 37, the contacts 41 when closed, to the The armature switch 17 thereupon engages its alter- :nate contact to establish a locking circuit for the relay. 37 which may be traced from the now grounded armature switch 47 through the winding of relay 37, the now engaged contacts 41, to the grounded battery 35. Circuit is consequently established for the magnet winding 4-3 which may be traced from the grounded terminal of relay 40, the winding of relay 110, one side of the calling line, the calling substation, the other side of the calling line, the normal contact 38 and its armature switch, the alternate contact 48 and its armature switch, the wiper 23, the waiting contact 18 or 20 engaged by the wiper 23, the winding of the device 43 to the grounded battery 35. When the magnet 43 is thus energized the ground is removed from the multipled selected contacts 27 so that when any wipers 24 engage contacts .27 from which the ground has thus been removed the circuit for the magnet 37 will remain open. so as to prevent the wipers oi" the moving switch from stopping, contacts 41 being closed when the wipers are in. engagement with waiting contacts and being open when out of engagement with said contacts. The wipers are stopped as a consequence of the opening of the motor winding circuit at 36 consequent upon the energization of the relay 37.

The selected operator, in response to the operation of her telephone receiver occasioned by the calling subscr1ber, ascertams 'the number of the line wanted.

At each operators position there is a key 50 serving when depressed to establish a circuit which may be traced from the grounded battery 35 through the interrupter 51, the key contacts 52, the left hand armature switch of relay 53 and its normal contact, the motor magnet 54, to ground. As a. consequence of the operation of the interrupter 51 the motor magnet is intermittently energized so that its armature intermittently operates a pawl 55 to step the ratchet wheel 56. This ratchet wheel 56 has an arm 57 fixed upon its shaft, this arm 57 carrying the wipers 13 and associate wipers later to be described, the wheel 56 stopping (by mechanism to be described) when the wipers 13 are located above the waiting contacts 11, 12 of a calling line. When the button 50 is depressed, a notch 58 in its shank is engaged by the nose of the armature of a magnet 59 so that the button 50 is held depressed until it is released upon the energization of the magnet 59, the armature of said magnet being withdrawn from the notch 58 when said magnet is energized, whereby the button 50 is restored and the contacts 52 are separated. When the button is restored the circuit for the magnet 59 is broken at 50 to restore the magnet to normal relation. The circuit for said magnet may be traced from the grounded battery 35, the winding of the magnet, the contacts 60, the waiting contact 57 (multipled as are the contacts 17, 18, etc.,) the wiper 58 the waiting contact 58 the wiper 58 the right hand armature switch of relay 53 and its normal follow-up contact, the winding of said relay, the now closed contacts 61, to ground, the energization of magnet 59 occurring when the wiper 58 (carried by arm 57) engages the waiting contact 58 in vertical alinement with the contacts 11, 12 of the calling line. When the magnet 53 is energized its armature switches engage their alternate contacts. The right hand armature switch of the magnet 53 thereupon establishes a locking circuit for said magnet which may be traced from the grounded battery 35, the winding of said magnet, the contacts 61, to ground. The left hand armature switch of magnet 53, when attracted, opens the circuit for the motor magnet 54 to stop the operation of the ratchet wheel 56. By the arrangement illustrated, ground is removed from contact 58 when it has engaged the waiting contact 58 pertaining to the contacts 11, 12 of a calling line so that the magnets 59 at other operators positions cannot be energized when their associate wipers 52-3 engage their contacts 58 Each link connector is provided with magnets 53 and 54. The motor magnets 54 associated with the different link connectors provided for each operator are partially governed by the left hand armature switches and the alternate contacts of preceding relays 53. .When the relays 53 are energized circuit for the motor'magnet 54 pertaining to the next link connector is partially closed at the alternate contact of the left hand armature switch of the relay 5301 Fig. 1 and the right hand armature switch of relay 53 of Fig. 2 and the normal contact of this latter relay. Thus the link connectors are brought into service in succession. The operator next makes and breaks a circuit by the circuit interrupter 62, such circuit being traced from the grounded battery 35, the armature switch of magnet 63, and its contact, the winding of motor magnet 64, the wiper 25 the waiting contact 25 the wiper 25, the Waiting contact 28 engaged by the wiper 25, to the key 62 and its grounded contact. The winding of motor magnet 64 is thereupon interrupted, the armature of said magnet thereupon causing pawl 65 to turn the ratchet wheel 66. The ratchet wheel 66 carries an arm 67 upon which the wipers 13 are mounted. The operator knows how far to step the wipers l3 and ceases the operation of the key 62 when the wipers 13 are brought over the contacts 11 12 When a wiper 13 is over the contact 11 a test circuit is established which is either opened or closed at the substation according to the busy or idle condition of the called line.

Assuming that the line desired is free, the operator includes a source of ringing current 49 in circuit with the called line by engaging the ringing key contacts 68. Aiter the desired subscriber has been called the operator manipulates the key 69 to establish a circuit through the wiper depressing magnet 70, the circuit established being traceable from the grounded contact of key 69, the waiting contact 29, the wiper 26 then engaging the same, the waiting contact 26 the wiper 26 then engaging the same, the normal follow-up contact of the relay 70, the winding of said relay, to the grounded battery 35. As a consequence, the relay 70 is energized to draw down its upper armature that is mounted upon the arm 57 to depress the wipers carried by said arm and bring the wipers 13 into engagement with the talking contacts 11, 12 of the calling line. When the relay or magnet 70 is energized, the mechanical connection 71 raises the pawl 55 to permit the ratchet wheel 56 to restore to normal when the relay 70 is later de'e'nergized, the relay 70 when energized holding the wiper supporting arm 57 from rotation, this arm being fixed with respect to the wheel 56, the arrangement shown in Fig. 3 being adaptable.

In Fig. 3 the core of the magnet 70 is extended so as to afford a non-rotating circular pole co-aXial with the toothed wheel 56. The arm 57 is connected with the disk 56 at its center so as to rotate with the disk while also movable toward and from the plane of'the disk. The armature for the magnet 7 0 is carried upon the arm 57 and overlies. the circular extension of the core of the magnet 70 so that the arm 57 may be attracted for the purpose of bodily moving the wipers, when rotated to position, in a direction transverse to their plane of rotation.

The wipers 13 and 7 3 constitute calling line terminals of a link connector which may be provided at its other end with a suitable connecting apparatus which may be located at the same or different exchange and which is suited to the plan of the system. I have equipped the other end of this link connector with operator controlled electro magnetic mechanism for further extending the link connector, in this case such operator controlled electro-magnetic mechanism serving to effect the connection of the link connector with a called line to which function the link connector, however, is not to be limited. The mechanism illustrated in Fig. 2 for con necting the link connector with a called line has mechanical structure illustrated in Fig. 3, the magnet 64 serving to step the ratchet wheel 66 around while the magnet 63 serves, when energized, to lift a pawl 65 and press the wipers 13 upon the waiting contacts 11 12 the elements 64 and 63 being similar in this respect to the elements 54 and 70 and it will not therefore be necessary to describe more in detail the mechanical a1- rangement of the elements 63, 64 and their associate parts. The motor magnet 64: is intermittently energized as a result of the operators key62 which serves to make and break the circuit of the magnet 64 a suilicient number of times to bring the wipers 13 over the waiting contacts 11 12 preparatory to the depression of these wipers by themagnet '63 if the desired line is found to be idle. It

' the desired lineis busy a noisy test circuit is established which is traceable from the grounded interrupter test magnet 74, the

right hand operators primary'coil, the test contacts 75 of an operators test key, the waiting contact 57, the wiper 58, the walting contact 13of the calling line, the wiper 13* engaging said contact 13 the upper wiper 13 the waiting contact 11 of the desired line, one side of the desired line and its substation, the other side of the desired line, the upper armature switch of relay 39 belonging to the desired line, the alternate contact of such armature switch, the armature switch of relay 40 individual to the desired line and its contact, the contact 72 of the desired line, the wiper 73, the armature switch of relay 70 and its alternate contact, to the grounded battery by way of the winding of relay 70. If the desired line is free, the operator includes the ringing generator 4:9 in circuit with the called line by engaging the ringing contact 68, the ringing circuit being traceable from the grounded generator 49 through the closed ringing contact'68, the waiting contact 57, the wiper'58, the waiting contact 13, the wiper 13*, the upper wiper 13 the contact 11 of the called line, one side of the called line, the switch hook 1 or the called line, to

- the grounded signal hell 4 at the called station. The-operator'does not manipulate the key 69 until the testing and ringing operations have been eiiected and consequently neither oi"- the magnets 2'0 and 63 is operated until the key 69 is operated and both of these magnets are operated together upon the'manipulation of tl e key 69, the magnet 70 being operated directly by the key 69 while the magnet 63 has circuit closed therethrough by the armature switch of magnet 70 when such switch is moved upon the energization of such magnet 70, the circuit for the magnet ("33 being traceable from the grounded battery 35, the winding of magnet sequence of the energization of the magnet .10, the key 69 being depressed for thispm'pose whether the calling line has secured connection with the desired line or not. lVhen the magnet 70 is energized its armature switch engages its alternate contact to establish a locking circuit through the magnet which may be traced from the grounded battery 35 through the winding of the magnet 70, its armature switch andthe alternate contact thereof, the armature switch of relay 40, the winding of relay 39, to ground. Another circuit is established which includes the magnet 40, the calling subscribers line, the upper armature switch of relay 39 and its alternate contact, the armature switch of relay 40, the waiting contact 72, the wiper 73 now pressed down into engagement with contact 72 by the magnet 70, the winding of magnet 70 and its alternate contact, and

the grounded battery 35. The calling subscriber thus has control of the magnet 40 when the operator responsive device selecting mechanism previously set into operation by the calling subscriber has been operated. to disconnect the callingsnbscribers line from the selected conductors leading to the selected operator. The magnet 70 will now remain energized as long as the calling subscribers telephone is free of its switch hook, the magnet 40 being deenergized when the calling subscriber restores his telephone upon its switch hook, whereupon magnet 70 is deenergized to open its circuit and release the arm 57 whereupon the wheel 56 is permitted to restore to normal (the pawl 55 having previously been disengaged) the wheel 56 in restoring to normal carrying with it the wipers fixed upon its shaft. hen the magnet 70 is dct nergizod it opens the circuit of magnet 63 so that the wipers 13 previously associated with the desired line are restored to normal. If the called subscriber has responded the magnet 40 will not be deenergized until the receivers at both stations are restored so that the wipers carried by the wheels 56 and 66 will not be restored until both subscribers replace their telephones upon their switch books.

The wipers carried by the wheel 56 having been depressed by the magnet 70. which operation is followed by the energization of the relay 39, the selector automatically set into operation by the calling subscriber for selecting the operators telephone or other responsive device of an idle operator, is

moved one step to a position in which the contacts 41 are separated and in which the conductors extending to the idle operator are disconnected from the wipers that previously had associated them with the calling line. This resnltis due to the separation of the upper armature switch of calling subscribers relay 39 from its normal contact whereby the circuit through the motor ma gnet 30 is opened, a circuit at the same time i being established through theu'pp er w indi-n g of the motor magnet that is traceable' from the lower grounded armature switch of relay 89, said upper winding of the motor magnet 30, the contacts al, to the grounded battery 35. The magnet 30 now operates to pull the ratchet wheel 21 to a position in which the contacts 41 are separated and in which the wipers carried by the wheel 21 are removed from engagement with the waiting contacts that were engaged thereby for the purpose of connecting anidle operator with a calling subscriber. The separation of the contacts 41 causes the relay 37 to be deenergized so as to dissociate the wipers carried by the wheel 21 from the calling line, these wipers now having been stepped into dead positions between waiting contacts.

It will be unnecessary to describe how the mechanism for selecting idle operators is prevented from being operated by respond ing called lines.

The keys or buttons 50 taken with their magnets 59 constitute testing or indicating devices, the keys, when released by the attraction of the armatures of magnets 59, serving to inform the operators when the calling line ends of the link connectors have become connected with calling lines. The magnets 59 and their associate keys 50 are individual to the operators as are also the contacts 60. The contacts 52 however are multipled through the various operators positions so that any operator may employ any idle switching mechanism for connecting a calling line with an idle link connector. As the link connecting mechanism would probably not be visible, the keys 50 serve, when released, to inform the operator when a link connector has been connected with a calling line. 7

In the specification and claims I have used the term link connector meaning thereby sections of telephone circuits each adapted for interchangeable connection with calling lines and with called lines, the operator being provided with means whereby a link connector may be brought into connection with any of several calling lines.

While I have herein shown andparticularly described the preferredembodiment of my invention 1 do not wish to be limited to the precise details of construction and. circuit arrangement shown as changes may readily be made without departing from the spirit thereof, but

Having thus described. my invention, I claim as new and desire to secure by Letters Patent the following 1. A telephone exchange system including telephone lines extending to an exchange; extensions for calling telephone lines; a. plurality of link connectors inclusive of operator controlled motor means for connecting the calling and called line ends thereof with calling lines and further extensions thereof;

and calling line operated selector switches for selecting unemployed link connectors, the connecting equipment for the link connectors adapting them to their line joining function independently of the selector switches.

2. A telephone exchange system including telephone lines extending to an exchange; extensions for calling telephone lines; a plurality of link connectors inclusive of operator controlled motor means for connecting the called line ends thereof with further extensions of calling lines; and calling line operated selector switches for selecting unemployed link connectors. the connecting equipment for the link connectors adapting them to their line joining function independently of the selector switches.

3. A telephone exchange system including telephone lines extending to an exchange; extensions'for calling telephone lines; a plurality of linkconnectors inclusive of operator controlled motor means for connecting the calling and called line ends thereof with calling lines and further, extensions thereof; and calling line operated selector switches for selecting link connectors, the connecting equipment for the link connectors adapting them to their line joining function independently of the selector switches.

i. A telephone exchange system including telephone lines extending to an exchange; extensions for calling telephone lines; a plurality of link connectors inclusive of oper ator controlled motor means for connecting the called line ends thereof with further extensions of calling lines; and calling line operated selector switches for selecting link connectors, the connecting equipment for the link connectors adapting them to their line joining function independently of the selector switches.

5. A. telephone exchange system including telephone lines extending to an exchange;

extensions 'for'calling telephone lines; a plurality of link connectors inclusive of operator controlled motor means for connecting the calling and called line ends thereof with calling lines and further extensions thereof; operators means for controlling the motor means; and calling line operated selector switches initially operated by calling lines when initiating calls and employed in the selection of operators means, the connect ing equipment for the link connectors adapting them to their line joining function independently of said selector switches.

6. A telephone exchange system including telephone lines extending to an exchange; extensions for calling telephone lines; a plurality of link connectors inclusive of operator controlled motor means for connecting the callingv and called line ends thereof with calling lines and further extensions thereof;

operators means for controlling the motor .1;

means; and calling line operated selector switches for selecting operators means, the connecting equipment for the link connectors adaptin'gthem to their line joining function independently of said selector switches.

7. A telephone exchange system including telephone lines extending to exchange operators positions; link connectors for joining telephone lines; motor means, less in number than the lines,'at the exchange for connecting called line ends of link connectors with lines 'to be joined with calling telephone lines; operator controlled means at the operators positions for governing the operation of the aforesaid means; selector switches operable by calling lines for selecting operator controlled means, the connecting equipment fort'he link connectors adapting them to their line joining function independently of the selector switches; and operators telephones associated with the operator controlled means. and in selectable relation to the selector switches that are provided with means for relating selected telephones to calling lines.

8. A telephone exchange system including telephone lines extending to exchange'operators positions; link connectors for joining telephone lines ;motor means, less in number than the lines, at'the exchange for connecting called line ends of link connectors with lines to be joined with calling telephone lines; operator controlled means at the operators positions for governing the operation of the aforesaid means; selector switches operable by calling lines for selecting operator controlled means, theconnecting equipment for the link connectors adapting them to their linejoiningfunction independently of the selector switches; and

calling line operated responsive devices associated with the operator controlled means and in selectable relation to the selector switches that are provided with means for relating selected responsive devices to calling lines.

9. A telephone exchange systemincluding telephone lines extending tofexchange oper ators positions; link connectors for joining telephone lines; motor means, less in number than the lines, at the exchange for connect ing calling line ends of link connectors with calling lines; motor means, less in number than the lines, at the exchange for connecting called line ends of link connectors with lines to be joined with calling telephone 7 lines; operator controlled means at the operators positions for governing the operation of the "aforesaid means; selector switches operable by calling lines for selecting operator-controlled means, the connecting equipmentfor the link connectors adapting them to their line oining function independently of the selector switches; and operators telephones associated with the operator controlled means and in selectable relation to the selector switches that are provided with means for relating selected telephones to calling lines.

10. A telephone exchange system including telephone lines extending to exchangev operators positions; link connectors for joining telephone lines; motor means, less in number than the lines, at the exchange for connecting calling line ends of link connectors with calling lines; motor means, less in number than the lines, at the exchange for connecting called line ends of link connectors with lines to be joined with calling telephone lines; operator controlled means at the operators positions for governing the operation of the aforesaid means; selector switches operable by calling lines for select-- ing operator controlled means, the connecting equipment for the link connectors adapting them to their line joining function independently of the selector switches; and calling line operated responsive devices associated with the operator controlled means and in selectable relation to the selector switches that are provided with means for relating selected responsive devices to calling lines.

11. A telephone exchange system inclnd-, ing telephone lines extending to an exchange, there being contacts pertaining to calling lines; extensions for extending calling lines, there being contacts belonging to these extensions for including them in circuit with calling lines; a plurality of link connectors each having contacts at the calling and called line ends thereof; motor means for effecting engagemei'it between the contacts at the calling line ends of link connectors and contacts pertaining to calling lines and for effecting engagement between the contacts at the called line ends of link connectors and contacts belonging to calling line extensions, the motor means associated with the calling line ends of the link connectors and also the motor means associated with the called line ends of the link connectors being less in number than the tele phone lines; operator controlled means at the operatorspositions for governing the operation of the motor means; and selector switches for selecting operator controlled means.

12. A telephone exchange system including telephone lines extending to an exchange, there being contacts pertaining to calling lines; extensions for extending call ing lines, there being contacts belonging to these extensions for including them in circuit with calling lines; a plurality of link connectors each having contacts at the calling and called line ends thereof; motor means for effecting engagement between the contacts at the calling line ends of link connectors and contacts pertaining to calling lines and for effecting engagement between the contacts at the called line ends of link connectors and contacts belonging to calling line extensions, the motor means associated with the calling line ends of the link connectors and also the motor means associated with the called line ends of the link connectors being less in number than the telephone lines; operator-controlled means at the operators positions for governing the operation of the motor means; and calling line operated selector switches for selecting operator controlled means.

13. A telephone exchange system including telephone lines extending to an exchange, there being contacts pertaining to calling lines; extensions for extending calling lines, there being contacts belonging to these extensions for including them in circuit with calling lines; a plurality of link connectors each having contacts at the calling and called line ends thereof; motor means for etlecting engagement between the contacts at the calling line ends of link connectors and contacts pertaining to calling lines and for eitecting engagement between the contacts at the called line ends of link connectors and contacts belonging to calling line extensions, the motor means associated with the calling line ends of the link conncctors and also the motor means associated with the called line ends of the link connectors being less in number than the telephone lines; operator controlled means at the operators positions for governing the operation of the motor means; and selector switches for selecting operator controlled means and link connectors.

14. A. telephone exchange system including telephone lines extending to an exchange, there being contacts pertaining to calling lines; extensions for extending calling lines; a plurality of link connectors each having contacts at the calling and called line ends thereof for connection with contacts pertaining to calling lines and their extensions; motor means, less in number than the telephone lines, for effecting engagement between contacts at the calling line ends of link connectors and contacts pertaining to calling lines; operator controlled means at the operators positions for governing the operation of the motor means; and selector switches for selecting operator controlled means and link connectors.

15. A telephone exchange system including telephone lines extending to an exchange,

there being contacts pertaining to calling lines; extensions for extending calling lines, there being contacts belonging to these extensions for including them in circuit with calling lines; a plurality of link connectors each having contacts at the calling and called line ends thereof; motor means for efiecting engagement between the contacts at the calling line ends, of link connectors and contacts pertaining to calling lines and for eiifecting engagement between the contacts at the called line ends of link connectors and contacts belonging to calling line extensions, the motor means associated with the calling line ends of the link connectors and also the. motor means associated with the called line ends of the link connectors being less in number than the telephone lines; operator controlled means at the operators positions for governing the operation of the motor means; and calling lineoperated selector switches for selecting operator controlled means and link connectors. 1

16. A telephone exchange system includ ing telephone lines extending to an exchange, there being contacts pertaining to calling lines; extensions for extending calling lines; a plurality of link connectors each having contacts at the calling and called line ends thereof for connection with contacts pertaining to calling lines and their extensions; motor means, less in number than the telephone lines, for efiecting engagement between contacts at the calling line ends of link connectors and contacts pertaining to calling lines; operator controlled means at the operators positions for governing the operation of the motor means; and calling line operated selector switches for selecting operator controlled means and link connectors.

17. A telephone exchange system including telephone lines extending to an exchange, there being contacts pertaining to calling lines; extensions for extending calling lines, there being contacts belonging to these extensions for including them in circuit with calling lines; a plurality of link connectors each having contacts at the calling and called line ends thereof; motor means for effecting engagement between the contacts at the calling line ends of link connectors and contacts pertaining to calling lines and for effecting engagement between the contacts at the called line ends of link connectors and contacts belonging to calling line extensions, the motor means associated with the calling line ends of the link connectors and also the motor means associated with the called line ends of the link connectors being less in number than the telephone lines; operator controlled means at the operators positions for governing the operation of the motor means; and calling line operated selector switches for selecting link 0011- nectors.

18. A telephone exchange system including telephone lines extending to an exchange, there being contacts pertaining to calling lines; extensions for extending calling lines; a plurality of link connectors each having contacts at the calling and called line ends thereof for connection with contacts per- 8 s 1,1 Ll' taining' to calling lines and'their extensions; lineoperated selector switches for selecting motor means, less in number than the telelink connectors. ,phone lines, for efiecting engagement be- In \vitness whereof, I hereunto subscribe tween contacts at the calling line ends of my name this third day of July A. D., 1912.

5 link" connectors and contacts pertaining to ELMER R. COR-VVIN.

calling lines; operator controlled means at \Vitnesses: the operators positions for governing the G. L. CRAGG,

E. L. WHITE.

operation of the motor means; and calling Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents Washington, D. C. 

